Hydrogels have been used in the literature in tissue engineering, in drug delivery, and as enzyme biomimics. Herein, we report the synthesis of a functional biomaterial using BSA as scaffold and epichlorohydrin as cross-linker. The hydrogels reported in this paper were shown to exhibit tunable pore size as a function of BSA concentration by scanning electron microscopy (SEM) and, therefore, are well suited to encapsulate drug molecules for delivery applications. These are injectable, shear thinning, self-healing, and has the ability to withstand a physical weight of ∼300 times of its own. In trypsin medium, the gel is degraded by 50% in 36 h supporting that these are biodegradable. The loading of Dox by the gel was confirmed by the emission of red fluorescence and also by filling the pores by fibrillar structures as demonstrated by SEM. The controlled release of Dox occurs over 5 days to an extent of 37 ± 2%, 26 ± 0.5%, and 21 ± 1.5% in PBS at pH 5.5, 6.8, and 7.4 respectively. Since these hydrogels are made of BSA as matrix, their biocompatibility was proven by MCF-7, HeLa, and MDA-MB-231 cells wherein 95 ± 5% of cells are viable when treated with unloaded hydrogel. However, the Dox loaded hydrogel results in 70–80% of killing in the case of all three cancer cells. Fluorescence microscopy and FACS studies support controlled and time dependent release of Dox in MCF-7 cells for 24 h where the drug goes into cytoplasm initially and then into nucleus. The cell cycle analysis carried out using MCF-7 cells clearly showed that the cell death is due to apoptosis, and this is by arresting the G2/M phase as a function of time. All of the data supports the utility of the synthesized BSA hydrogel as a biomaterial that will find application in controlled drug delivery.

A nitrobenzoxadiazole (NBD)-appended calix[4]arene conjugate (L) possessing a cyclic core formed by connecting the 1,3-positions at the lower rim has been designed. The L has been developed as a receptor for the selective recognition of biologically and ecologically relevant trivalent metal ions, viz., Cr 3+ , Fe 3+ , and Al 3+ . The interaction and region of binding of these metal ions by the receptor L have been explored by isothermal titration calorimetry, spectroscopy, microscopy, and density functional theory (DFT) computational studies. The probe L itself exhibits weak fluorescence emission intensity, and the quantum yield is enhanced by ∼4-fold upon addition of the M 3+ ion due to the chelate enhanced fluorescence effect. Fluorescence enhancement also takes place in L when it interacts with M 3+ even in the solid state and in the MCF7 cancer cells. The binding constant (K b ) for M 3+ by L is ∼10 4 M −1 , supporting that these ions bind to L with moderate strength. The detection limit for all the three metal ions is as low as 4−5 μM. The 1 H NMR data reflects the region of binding of the M 3+ ion to L. The binding is further supported by DFT studies where the space filling structures evidently shows the binding core in L, and the M 3+ ion is buried in this core. As a result of this, the microscopy features are almost the same for L and {L + M 3+ }. The reversible utility of the sensor has been achieved by the addition of H 2 PO 4 − . Based on the input−output information, a molecular logic circuit (INHIBIT logic gate) has been built, which will provide an electronic basis for designing a memory device by the concerned experts.

A calix[4]arene conjugate possessing a tetrapyrenyl moiety at its upper rim (R) is designed as a receptor for sensing trinitrophenol (TNP). To understand the role of the calix[4]arene platform and that of pyrenyl moieties in R, two other control molecules were synthesized. These are as follows: the one possessing a tetraphenyl moiety in place of tetrapyrenyl (R1) and the other one is a p-pyrenyl-hydroxy benzene (R2) that is devoid of the calix[4]arene platform. The R shows high sensitivity toward TNP in tetrahydrofuran (THF) over eleven other nitroaromatic compounds (NACs) studied by exhibiting large fluorescence enhancement and hence is selective to TNP over the other NACs studied. However, the control molecules R1 and R2 showed only marginal fluorescence enhancement, supporting the need of a calixarene platform and the presence of a tetrapyrenyl moiety in the receptor system for the selective sensing of TNP. Further, R1 and R2 are not suitable for sensing, since these exhibit similar fluorescence response over several NACs studied. The binding of TNP by R has been addressed by fluorescence titration and isothermal titration calorimetry. The nature of the complexation of TNP by R has been revealed by the computational calculations, wherein the data showed the entrapment of TNP by two adjacent pyrene moieties via π–π stacking interactions. Such host–guest complexation is expected to restrict the mobility of the pyrene moieties present in R. The reduction of the flexibility of the pyrenyl moieties of R upon TNP binding is evidenced by the 1H NMR spectral study, wherein this acts as an additional evidence for the complexation. In the present study, the sensing of TNP by R has been shown in THF solution, on the surface of silica gel and the cellulose paper to result in lowest detection limits (LODs) of 1.5, 3.5, and 6.5 μM, respectively. Even the solid mixture of R and TNP showed LOD of 2.1 μmol. Since R is expected to show supramolecular aggregation that is dependent on the guest species, the corresponding details were probed by microscopy techniques, using scanning electron microscopy, atomic force microscopy, and transmission electron microscopy methods, and significant changes in the aggregation of R upon interaction with TNP were found. Such aggregation is responsible for the observed fluorescence enhancement. Thus, the tetrapyrenyl calix[4]arene conjugate (R) acts as a sensitive and robust platform for selective detection of TNP from a mixture of nitroaromatic compounds (NACs) wherein the fluorescence intensities can be imaged and managed by a cellular phone.

A new bimodal fluorescent cationic calix[4]arene (L) conjugate has been synthesized in multiple steps and well characterized by NMR and electrospray ionization-mass spectrometry (ESI-MS) techniques. L has been investigated for its DNA binding ability by various spectroscopy techniques like absorption, fluorescence, and circular dichroism (CD). The formation of L-DNA complex has been confirmed by the gel electrophoresis in the presence of incremental concentration of L. To visualize the packing of the plasmid (pBR322), detailed tapping mode atomic force microscopy study has been performed, which revealed blob-like structure of plasmid upon addition of the incremental amount of L. Concentration dependent transfection ability of L has been established in MCF-7 cells by confocal microscopy by carrying the red fluorescent protein (RFP) encoded plasmid pCMV-tdTomato-N1 to emit both intrinsic fluorescence of L as well as that from RFP. All this has been possible in the absence of any adjuvant phospholipids (DOPE) that are commonly used as helper. Further transfection efficiency of L has been compared with the commercially available lipofectamine (LTX) in two cancer cell lines, MCF 7 and SH-SY5Y, and found that the L is as efficient as that of LTX. Hence, L is an efficient and effective cargo to transport genetic material into the cells.

The availability of potable water is one of the major concerns in many countries today. This brings in a need to design molecular scaffolds suitable for efficient adsorption of the contaminants present in water. In this paper, an unprecedented strategy is demonstrated in order to synthesize highly porous bovine serum albumin_Au (BSA_Au) beads and was employed for the removal of water contaminants. The beads stored in acidic medium (Beada) and in basic medium (Beadb) selectively adsorb anionic and cationic species that includes organic dyes and inorganic species, respectively, by showing a pH-responsive behavior. This phenomenon bestowed the beads with the recyclability and reusability as demonstrated for eight cycles wherein almost 100% efficiency is retained by the beads without any deterioration. The porous nature of these beads is retained even after switching the pH for several cycles of adsorption–desorption processes as judged based by the SEM data. Thus, the reported beads are demonstrated for their selective and efficient removal of both organic and inorganic contaminants from water wherein the beads can be recycled by triggering pH changes that would also release the captured species. The biologically benign beads act as reusable smart nanofactories in the purification of water from industrial contaminants.

The magnetic iron oxide nanoparticles were coated with a fluorescent torch and were further tagged with wheat germ agglutinin so as to direct the resulting nanocomplex selectively towards breast cancer cells in order to deliver the drug.

This paper deals with the synthesis of a protein–inorganic hybrid hydrogel and its derived materials, including aerogel and sheet, and the demonstration of their application potentials. For this, a common and abundant protein, bovine serum albumin (BSA), and a copper salt were used in order to prepare a hydrogel by cross-linking the protein molecules using epichlorohydrin and embedding Cu2+ ions to give BSA_Cuhydrogel (1). When this material was lyophilized, it resulted in the product powder BSA_Cuaerogel (2); however, when dried under vacuum, it yielded a blue sheet material, BSA_Cusheet (3). All three of these biomaterials were characterized by spectroscopy and microscopy and further studied for three different applications, and the data were compared in order to establish the material vs property/activity relationship. The applications include (i) adsorption of organic dyes, (ii) reductive degradation of these dyes, and (iii) the reductive transformation of nitroaromatic compounds. The study revealed the efficient adsorption of the anionic and neutral dyes, while the adsorption of the cationic dye was much lower. The adsorption capacities (in mg/g) of Congo red followed the trend BSA_Cuaerogel (367 ± 6) > BSA_Cuhydrogel (274 ± 4) > BSA_Cusheet (204 ± 3). The comparison of the rate of reductive degradation of Congo red and methylene blue follows the same trend as that of the adsorption of the dyes. The reductive degradation was demonstrated for six cycles by reusing the recovered catalyst after every cycle. More than half a dozen nitroaromatics were studied for their reduction using BSA_Cuaerogel. In the case of p-nitrophenol, the rate of reduction follows the trend 2 > 1 > 3. Thus, this paper deals with a methodology to synthesize both a robust hydrogel incorporating metal ions and other derived protein-based biomaterials, viz., an aerogel and sheet, and a comparison of their activity toward the adsorption and degradation of dyes and nitroaromatics.

A fluorescent naphthalimide conjugate of calix[4]arene ( L 1 ) has been synthesized and characterized. The selective and efficient detection of trinitrophenol (TNP) by L 1 among nine other different nitroaromatic compounds was demonstrated using absorption and fluorescence spectroscopy. The minimum detection limit is 29 nM, which is the lowest reported so far by any conjugate of calixarene toward TNP. The fluorescence quenching is associated with a high Stern–Volmer constant of 3.3 ± 0.4 × 10 5 M –1 . The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) data revealed a network structure with pores having a weighted average size of 0.66 ± 0.08 μm for L 1 . When incubated with TNP, the pores were filled with fibril structures, as supported by both SEM and TEM data. In order to demonstrate the real time applications, the L 1 has been coated onto a Whatman filter paper and the imprint of TNP contaminated thumb has been detected upon physical contact. The 1 HNMR titration and the studies carried out using the control molecule support the necessity of both the naphthalimide moiety and the calixarene platform for sensing. In order to mend L 1 as a reversible sensor for TNP, the same is incorporated into carrageenan beads ( L 1 @ C b ) and the reversible sensing has been shown for three cycles by reusing the same material upon recovery followed by washing it. The solid-state detection of TNP has also been demonstrated using the lyophilized L 1 @ C b bead powder. The fluorescence intensity of L 1 was quenched upon addition of solid TNP to the lyophilized bead powder of L 1 @ C b as studied by fluorescence microscopy. The computational studies show that one of the arms of the calixarene takes a bent conformation, and the 1:1 TNP complex of L 1 is stabilized by exhibiting differential extents of hydrogen bonding interactions with the two arms owing to their conformational difference. The result of such complexation was already felt through the shifts observed in the experimentally measured 1 HNMR spectra.